The present invention relates to a reconfigurable part supporting and positioning fixture, particularly, but not exclusively, for machine-measured parts.
In the following description, specific reference is made to the above application purely by way of example.
As is known, for measuring parts on a measuring machine, the parts are positioned and secured to the machine bed by means of supporting fixtures. These are normally special-purpose types and, particularly in the case of parts deformable under their own weight, such as certain vehicle body components, are relatively complex and expensive by having to reproduce the in-service restraint conditions of the part.
As an alternative to traditional special-purpose fixtures, to reduce retooling cost for measuring different parts, reconfigurable fixtures have been devised, as described for example in Italian Patent n. 1.206.886 filed by the present Applicant.
Briefly, such fixtures consist of a number of column type supporting elements substantially comprising a base secured in a predetermined position to the reference surface, e.g. by means of magnetic stops, and a rod adjustable in height along an axis perpendicular to the reference surface. Both positioning of the base and the height adjustment of the rod are performed automatically by the measuring machine itself, the head of which is equipped with a gripping tool cooperating with the column elements.
Though highly effective, known reconfigurable fixtures of the above type present several drawbacks. First and foremost is the high cost involved, mainly due to the complex mechanical design and circuitry of the column elements and gripping tool for rendering the fixture fully automatic.
Secondly, as the base is supported pneumostatically on the reference surface, whereas it is locked in any position magnetically, the reference surface of the machine must be made of ferromagnetic material with none of the holes normally provided on conventional machines, which means fixtures of the above type cannot be used on conventional machines of all types.